Determination of fiber characteristics in paper making



M. A. KEYES Aug. 122.1969

DETERMINATION OF FIBER CHARACTERISTICS IN PAPER MAKING Filed Oct. 22, 1965 5 Sheets-Sheet 1 ATTORNEYS Aug. 12, 1969 M. A. KEYES 3.461.030

DETERMINATIONOF FIBER CHARACTERISTICS IN PAPER MAKING Aug. l2, 1969 `M. A. KEYES Filed Oct. 22, 1965 5 Sheets-Sheet 5 DETERMINATlON OF FIBER CHARACTERISTICS IN PAYER MAKING Filed Oct. 22, 1965 M. A. KEYES Aug. 12, 1969 5 Sheets-Sheet 4 ux 12, 1969 MVA. KEYES 3.461.030

DETERHINATION oF FIBER cHARAcTRIs'rics 1N PAPER MAKING Filed oct. 22. 196s '5 sheets-sheet s ELE-..

INVENTOR. M42/o Ke-Yes 3,461,030 DETERMINATION F FIBER CHARACTERISTICS IN PAPER MAKING Marion A. Keyes, South Beloit, Ill., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Oct. 22, 1965, Ser. No. 501,767 Int. Cl. D21f 11/00 U.S. Cl. 162-198 7 Claims ABSTRACT OF THE DISCLOSURE Apparatus for measuring the size of fibrous particles in paper pulp and which measures the length, crosssectional area and volume of the fibers is disclosed. The apparatus allows measurement of liber particle sizes to be made as a continuous process without interrupting the Operation of the paper making machine. The measurements made are used to control the size of the particles being fed into the paper machine. Also, the conductivity of the paper pulp is regulated and the rate of ow through the machine is controlled.

This invention relates generally to an apparatus for measuring size of fibrous particles and the like and more particularly to a system for measuring the length, crosssectional area, and volume of individual fibers. Particularly, this invention relates to an apparatus used for measuring fibrous particles used in the paper-making industry in such a manner so as not to disturb the continuity of the paper-making process. More specifically, this invention relates to an apparatus for measuring various constituents of ibrous'particles of pulp and to develop control signals indicative of the value of such constituents to automatically control the paper-making machine during the paper-making process.

The size of the individual fibers in a pulp stock or slurry determines many of the resulting characteristics of the finished paper web. This ber size is variable and is dependent upon many factors which contribute to the making of the pulp stock. For instance, the type and moisture content of the wood, the chipping and pulping mechanisms employed, and other methods and apparatus employed in the manufacture of paper pulp contribute to variations in fiber size. These variations are also attributable to minute factors, such as the amount of Water employed in the chipping and pulping processes and the speed of operation of the chipping and pulping apparatus.

Since the fiber size in a particular pulp stock is variable and since the fiber size determines many of the resulting characteristics of the finished paper web, it is desirable to provide some means of determining the size of individual fibers. Such a determination or measurement could then be employed to adjust the input to the paper machine to alter the fiber size accordingly.

Prior methods and techniques for measuring individual fiber size of a paper stock have required inspection of random samples, usually under a microscope. This process is relatively slow and cumbersome and, at best, is only as accurate as the individual making the inspection. In addition, since such a process is slow, and relatively few samples can be inspected, the samples inspected may not be an accurate representation of the entire stock.

Another important factor in maintaining the resulting paper web within prescribed requirements is that of the consistency of the pulp stock. Since the consistency can be determined by multiplying the total liber volume per milliliter counted by the dry liber density (which is determined empirically), a system for measuring the size of fibrous particles is useful in such determination. Such a fiber size measuring system is also useful in determining United States Patent O 3,461,030 Patented Aug. 12, 1969 "ice headbox consistency, since that parameter is determined by multiplying the previous mentioned consistency value by the dilution factor.

It is, therefore, one primary object of the present invention to provide an apparatus which can measure size parameters of wood pulp fibers which are variable during the entire paper-making operation and, in accordance with the measured information, provide suitable control functions to the paper-making machinery so as to consistently produce the desired grade and quality of paper.

Another object of the present invention is to provide an apparatus for measuring the average length of the fibrous particles used in the manufacture of paper.

Another object of the present invention is to provide an apparatus for measuring the average cross-sectional area of fiber particles used in the manufacture of paper.

Still another object of the present invention is to provide an apparatus for measuring the total volume of fibrous material used in the manufacture of paper.

Still another object of the present invention is to provide a method and apparatus for determining the consistency of a pulp stock.

And a further object of the present invention is to provide a method and apparatus for determining headbox consistency.

Yet another object of the present invention is to provide an apparatus for measuring desired constituents of fibrous material from samples taken directly from a paper-making machine and thereafter to produce suitable control signals to effect control of the paper-making machine without interrupting the continuity of the papermaking process.

A feature of the invention resides in the provision of a maximum value detector which senses pulse signal information indicative of individual fiber size and converts such pulse signal information into continuous signal information having a maximum amplitude representative of fiber size.

These and other objects, features and advantages will be realized by the novel structure of the invention which includes means for removing a sample of fibrous pulp from a particular station of a paper-making machine without disturbing the continuity of the paper-making process and measuring `device for determining individual fiber sizes. Also, there is provided means for adding a controlled amount of diluting uid into the stream of the sample of fibrous material to reduce the number of fiber particles per unit volume of solution which is sampled. Additionally, there is provided means for adding electrolyte solution into the stream of the diluted sample so as to render the sampling solution electrically conductive. Thereafter, the fiber particles of the sample, which are now suspended in a relatively large volume of conductive fluid, pass through an aperture of a sensing head of the measuring device in such a manner as to produce signals in the sensing head indicative of particle size. The signal information from the sensing head is then delivered to suitable amplifier and control means for accurate control of the paper-making apparatus.

The invention, however, will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings in which like reference numerals throughout the various views of the drawings are intended to designate similar elements or components and wherein:

FIGURE l is a schematic block diagram of a pulp sampling system for measuring the size of fibrous particles to produce a signal pulse indicative thereof, which system is Vconstructed in accordance with the principles of this invention;

FIGURE 2 is a schematic block diagram of a fiber length analyzer which may receive signal pulses from the sampling system of FIGURE l;

FIGURE 3 is a schematic block diagram of a fiber diameter analyzer which receives signal pulses from the sensing head of FIGURE 1;

FIGURE 4 is a schematic block diagram of a consistency analyzer which may receive signal pulses from the sampling system of FIGURE 1 so as to measure the relative consistency of the fibrous pulp;

FIGURE 5 is a schematic block diagrams of a length and/or diameter analyzer which may receive signal pulses from the sampling system of FIGURE l to provide a measure of the total volume of the libers by adding the volume of each ber passing through the sampling system of FIGURE l; and

FIGURE 6 is a schematic wiring diagram of a maximum value detector which may be used in FIGURES 2 and 4 and which is constructed in accordance with the principles of this invention.

- IGURE 1 is a schematic block diagram of a pulp sampling system which is designated generally by reference numeral 10. A sampling device 11 is provided for taking pulp samples from a paper-making machine (not shown). The pulp sample is delivered to a sensing head v12 where individual vfibers of the pulp sample pass through an aperture 13 to derive pulse signal information at an output lead 14. The pulse signal information is then delivered to a counter 15 which may be used to count either the total length of all the fibers passing through the aperture 13 and/or the total cross-sectional area of all the fibers passing through the aperture 13.

The sampling device 11 delivers a sample of pulp stock to a conduit 21. A flow meter 16 is connected into the conduit 21 and measures the quantity of pulp stock flowing therethrough. This measurement is sensed by a transducer 17 and provides a signal to a iiow indicating control 18 in accordance with the metered flow. A ratio recording controller 19 is connected to the control 18 for further processing of the information. A valve 20 in the conduit 21 is connected to and controlled by the flow ndicating control 18. The valve 20 regulates the flow of pulp sample through the conduit 21.

A supply of diluting water 22 has the output thereof connected to a source of electrolyte solution 23 through a control valve 24. The mixture of diluting Water and electrolyte solution is delivered to a flow meter 26 which has associated therewith a transducer 27. Electrical signal information is delivered to the ratio recording controller 19 through a lead 28. A set point actuator 29 is associated with the ratio recording controller 19 to provide means for adjusting the proper ratio between the quantity of pulp sample and the quantity of diluting uid added thereto. The -ratio recording controller 19 is connected to and controls a valve 30 which is in fluid communication With the ow meter 26 for controlling the quantity of diluting uid delivered from the supply 22 and mixed with the electrolyte solution.

The desired quantity of electrically conductive diluting fluid passes through a pipe 31 which is in uid communication with the pipe 21. As seen in FIGURE l, the electrically conductive diluting iuid is mixed with the pulp sample in the piping 21 whereupon the mixed uid continues to ow through a single fluid path.

A heater 32 is placed in proximity with the conduit 21, as seen in FIGURE l, and is connected to a source of alternating current 33 through a potentiometer 34. A heat sensitive transducer 36 is associated with the conduit 21 so as to sense the relative temperature of the uid mixture passing therethrough to derive control signals which are representative of the fluid temperature. The control signal from the transducer 36 is delivered to a temperature indicator control 37 which is electro-mechanically connected to a control knob 38 of the potentiometer 34, as indicated by a dotted line 39. The heater 32, the transducer '36, and the temperature indicator control 37 form a closed loop temperature control system for the fluid in the conduit 21.

The mixed uid within the conduit 21 passes through a conductivity cell 40. A transducer 41 is associated with the conductivity cell 40 for producing electrical signal information indicative of the electrical conductivity of the iluid passing therethrough. The electrical signal information from the transducer 41 is then delivered to a conductivity controller 42 which is connected to the control valve 24 as indicated by the dotted line 43. In this manner, the amount of electrolyte solution which is mixed with the diluting water is accurately controlled within prescribed limits.

The uid passes through the conductivity cell 40 and is delivered through a conduit 44 to the sensing head 12. The sensing head 12 may be provided with suitable overow means 45 so as to allow the fluid carrying the pulp sample to pass through the sensing head and be disposed of or returned to the headbox.

The sensing head 12 is provided with a pair of electrodes 46 and 47 disposed on opposite sides of the aperture 13. The electrode 46 is connected to a supply of direct current voltage through a load resistor 46a or the like, while the electrode 47 is connected to ground. To maintain each fiber of the pulp sample substantially suspended within the electrically conductive diluting fluid an agitator 49 is provided within the sensing head 12. By way of illustrative example, the agitator 49 may be connected to an air-operated drive mechanism 50.

The sensing head 12 is an electronic device which measures liber size within the range of 1 to 1000 microns in diameter by displacement of electrolyte solution within the aperture 13. A continuous voltage drop is provided between the electrodes 46 and 47 which is determined by the conductivity of the electrolyte solution and the diameter of aperture 13. As a particle passes through the aperture 13, the ion flow through the aperture is momentarily impeded thereby causing an increase in voltage developed between the electrodes 46 and 47. The amount of voltage change between the electrodes 46 and 47 is determined primarily by the relation of fiber cross-sectional area and the size of aperture 13.

Shown in FIGURE 2 is one arrangement of a fiber length analyzer which is constructed in accordance fwith the principles of this invention. Pulse signal information from the sensing head 12 is delivered to an amplifier 61 wherein the electrical impulses are amplified. A clipper and ampliier 62 receives the amplified signal from the amplifier 61 and clips the signal to a predetermined value whereupon the signal is delivered to an integrator 63. Each output pulse or signal of the clipper 62 is of constant amplitude but of varying time intervals. Therefore, the integrator 63 produces a saw-tooth pulse of an amplitude determined Iby the pulse width of each pulse signal received from the clipper 62.

The output signal of the integrator 63 is delivered to a maximum value detector 64 which converts the sawtooth pulse to a direct current voltage having substantially the same amplitude as the saw-tooth pulse. An analogue to digital converter 66 receives the direct current voltage from the maximum value detector to derive a digital control signal indicaitve of the amplitude of the direct current voltage. The output of the analogue to digital converter 66 is delivered to a computer 67 which automatically computes the average length of the fibers sampled.

In operation, the flow rate of the electrically conductive diluting lluid is maintained constant through the orice 13, of FIGURE l, so that the pulse width generated within the sensing head 12 is indicative of fiber length. Therefore, the maximum output of the integrator 63 is proportional to the maximum fiber length passing through the aperture 13. The maximum value detector 64 detects and holds the maximum output from the integrator 63. After the ber has passed completely through the orifice 13, the analogue to digital converter 66 provides digital where zaverage length of the fibers, and L: average length of the fibers, and nznumber of fibers.

Shown in FIGURE 3 is a block diagram of one arrangement of a fiber diameter analyzer which is constructed in accordance with the principles of this invention. The sensing head 12 delivers pulse signal information to an amplifier 71. The output signal from amplifier 71 is delivered to a threshold circuit 72 which is connected to a delay circuit 73. A sample control circuit 74 receives the signal information from the delay circuit 73 to deliver a signal to a sample and hold circuit 76. The output signal from amplifier 71 is also delivered to the sample and hold circuit 76 as seen in FIGURE 3. The sample and hold circuit 76 is gated or controlled by the sample control 74. This gating signal is dependent upon the threshold circuit 72. Coincidence of two or more fibers is eliminated by delaying the pulse sampling for a time equal to the time of passage through the orifice 13 (FIG- URE l) of a fiber of threshold length. This threshold length is pre-set into the threshold circuit 72 and any signal in excess of such length will not allow gating of the sample and hold circuit 76. If the signal is within the prescribed length range, the signal from the sample and hold circuit will be gated to an area to diameter converter 77. It is unlikely in this control function that the coincident fiber could be close to the end of the primary fiber (0.05 mm.) and yet the effects of non-uniform fiber ends will have been eliminated. Further limitation can be effected by using this sampling technique and comparing the held sample value to the output of a maximum value detector. When the discrepancy in such a system is greater than, for instance, three standard deviations of the peak signal value (as determined from large dilutions separately) the diameter figures could be rejected. Therefore, in the system as illustrated, the delay is introduced to sample average diameter of the fiber shortly after the fiber enters the sensing orifices. This delay avoids the possibility of two fibers being overlapped which would provide an erroneously high reading.

The sample and hold circuit 76 provides a pulse of uniform height, depending upon the area of the fiber sampled, when the sample control 74 gates the input thereto. The output of the area to diameter converter 77 is delivered to an analogue to digital converter 78. The output of converter 73 is delivered to a digital computer 79 whereupon the computer 79 displays information indicative of mean fiber diameter, standard deviation, skewness of fibers passing through the aperture 13, and equal distribution points for graphical analysis.

Should it be desired to utilize the analogue information provided yby the area to diameter converter 77 an analogue computer 81 may be connected thereto as indicated by dotted line S2.

Shown in FIGURE 4 is a block diagram of a consistency analyzer which is constructed in accordance lwith the principles of this invention. An amplifier 84 is connected to the sensing head 12 for amplifying the pulse signal information therefrom. The output of amplifier 84 is delivered to a clipper amplifier 86 which, in turn, delivers the amplified and clipped signal to an integrator 87. The output of integrator 87 is delivered to a maximum value detector 88 whereupon a direct current voltage is developed having an amplitude indicative of the maximum value of the integrated pulse delivered thereto.

Pulse signal information from amplifier 88 is also delievered to a threshold circuit 89 which is part of a sampling control 90. The signal from the threshold 89 is delivered to a delay circuit 91 and therefrom through a sample control circuit 92. The output of sample control circuit 92 is delivered to a sample and hold circuit 93 which also receives pulse signal information directly from amplifier 84, as seen in FIGURE 4.

The output of the sample and hold circuit 93 is indicative of fiber area and is delivered to a multiplier circuit 94 and to analogue or digital computer 96. Also delivered to the multiplier 94 is the direct current voltage from the maximum value detector 88 through a line 97. The direct current voltage from maximum value detector 88 is also delivered to the analogue digital computer 96 through a line 98.

The output of the sample and hold circuit 93 and the output of the maximum value detector 88 are multiplied together within the multiplier circuit 94 and a signal indicative thereof is delivered to the analogue digital computer 96 through a line 99. Therefore, signal information indicative of fiber area is delivered to the computer 96 through the line 95, while signal information indicative of fiber length is delivered to the computer 96 through the line 98, and finally signal information indicative of fiber volume is delivered to the computer 96 through a line 99. In this manner, all the parameters pertaining to the physical constituents of fibrous pulp can be automatically analyzed and suitable control signals can be developed to automatically control the operation of a paper-making machine.

The fibrous pulp consistency is determined by multiplying the total fiber volume per milliliter counted by the dry fiber density, which may be determined empirically. By way of example, the fibrous pulp consistency within the headbox of a paper-making machine may be computed from this figure by multiplying it by the dilution factor.

Show in FIGURE 5 is a schematic block diagram of a fiber length and diameter analyzer which is constructed in accordance with the principles of this invention. Pulse signal information from the Sensing head 12 is delivered to an amplifier 101. The output signal from amplifier 101 is divided and delivered to a length determining circuit 102 and to a diameter determining circuit 103. The length determining circuit 102 consists of a clipper amplifiel 104, an integrator 106, a threshold circuit 107, and a counter 108. Amplified signals from amplifier 101 are further amplified and clipped by circuit 104 and delivered to the integrator 106 wherein saw-tooth pulses are generated the amplitude of which is indicative of fiber length. The sawtooth pulse is delivered to the threshold circuit 107 where- 1n the pulse is compared with a threshold or reference voltage and pulses exceeding the threshold voltage are delivered to the counter 108 for tabulation. The counted pulses are then delivered to a computer 109 which has an output thereof connected to a servo drive 110 which, in turn, is connected back to the threshold circuit 107 for control thereof.

The output pulse from amplifier 101 is also delivered to a threshold circuit 111, of the diameter determining circuit 103. The pulse information exceeding the threshold reference voltage derived within the threshold circuit 111 is delivered to an amplifier 112 and therefrom to a counter 113 for tabulation. Output signals from counter 113 are delivered to the computer 109 for evaluation. The cornputer 109 has an output thereof connected to a servo drive 114 which is provided for controlling the operation of the threshold circuit 111.

By way of example, the maximum threshold signal may be selected as being two or three increments below a normal signal value of the particles counted. Therefore, as the average value changes, of the particles being evaluated, the computer 109 energizes the servo drive 114 to automatically adjust the setting of the threshold vcircuit 111. The threshold 107 is controlled by the servo drive 110 to perform substantially the same function as mentioned hereinabove.

Shown in FIGURE 6 is a schematic wiring diagram of a maximum value detector which is constructed in accordance with the principles of this invention. The maximum value detector 64, which is shown in FIGURE 2, may be substantially the same as the maximum value detector 88 shown in FIGURE 4. An input terminal 120 is provided for receiving integrated input pulses in the form of sawteeth. The pulse signal information is delivered to a terminal point 121 through a resistor 122. An amplifier 123 has an input thereof connected to circuit point 121. Shunting the amplifier 123 is a diode 124. Connected in series with the output of amplifier 123 is a diode 126 which, in turn, has one end thereof connected to the circuit point 121 through a resistor 127.

Pulse signal information applied to terminal 120 is inverted at the output of amplifier 123. Therefore, an inverter 128 is connected to the output of amplifier 123 through the diode 126. The inverted signal information is then applied to an output terminal 129.

The output of amplifier 123 is delivered to a capacitor 130 through a line 131. Connected to the other lead of capacitor 130 is a circuit point 132 which, in turn, is connected to an input of an amplifier 133. Shunting the amplifier 133 is a diode 134. Connected between the output of amplifier 133 and the line 131 is a resistor 136.

A reset relay 137 has associated therewith a contactor 138 which is actuated to reset the maximum value detector 64. A negative supply voltage is delivered through a contact 139 to a current limiting resistor 140 through the closed contactor 138. The negative voltage then appears at circuit point 132 thereby resetting the maximum value detector.

THEORY OF OPERATION OP MAXIMUM VALUE DETECTOR A continuously increasing positive signal voltage is applied to terminal 120 and therefrom to circuit point 121 to render the amplifier 123 conductive. The output voltage of amplifier 123 is negative thereby allowing current to flow through series diode 126 into the line 131. The negative signal at terminal 132 is then amplified and inverted by amplifier 133 in such a manner as to produce a positive signal at the output thereof which, in turn, causes current to fiow through diode 134 back to circuit point 132 to maintain the amplifier 133 continuously energized. It can be seen therefore that the lead of resistor 136 connected to amplifier 133 has a positive potential applied thereto, and the lead of resistor 136 connected to line 131 has a negative potential applied thereto. This causes current to iiow through resistor 136 and diode 134 to maintain the amplifier 133 energized. Furthermore, the line 131 is continuously held at a negative potential equal to the maximum value of the positive potential applied to the terminal 120. The negative signal information on line 131 has been inverted by inverter 128 and applied to the output terminal 129.

After a predetermined time interval, the reset relay 137 is energized thereby actuating contactor 138 and applying a negative voltage to circuit point 132 thereby placing the maximum value detector 64 in condition to receive another pulse signal.

I claim as my invention:

1. The method of measuring size of fibrous particles of paper pulp comprising the steps of:

(a) detecting the rate of flow of said paper pulp,

(b) controlling the rate of flow of said pulp as a function of the detected rate of flow,

(c) adding electrically conductive uid to said paper pulp,

(d) detecting the conductivity of the pulp after the electrically conductive fluid has been added,

(e) controlling the quantity of electrically conductive fluid added to said pulp as a function of the detected conductivity, and

(f) electrically sensing the size of particles in the paper pulp and electrically conductive fluid. v

2. An apparatus for measuring predetermined constituents of fibrous particles as they pass through a paper making machine comprising: (a) a conduit means for receiving a small quantity of pulp from the normal flow of pulp passing through the machine during the paper making process, (b) first valve means in said conduit means, (c) ow detecting means connected in said conduit means before said first valve means for controlling said first valve which controls the quantity of pulping samples, (d) means for supplying electrolyte solution to said conduit after said first valve means, (e) means for sensing the conductivity mounted in said conduit at a position after the electrolytic solution has been added, (f) said means for supplying electrolyte solution including second valve means, (g) a controller connected to said second valve means and to said means for sensing the conductivity for controlling said second valve, (h) sensing means in said conduit after the means for sensing the conductivity, (i) said sensing means including electrode means for producing an electrical pulse signal indicative of fiber size as each of the fibers pass through the aperture of said sensing means, and (j) means connected to said electrode means for analytically measuring a particularconstituent of each fiber of the pulp sample.

3. An apparatus for measuring predetermined constituents of fibrous particles as they pass through a paper making machine comprising: (a) a conduit means for receiving a small quantity of pulp from the normal flow of pulp passing through the machine during the paper making process, (b) a first valve means in said conduit means, (c) iiow detecting means connected in said conduit means before said first Valve means which controls the quantity of pulp being sampled, (d) a second valve means with its output connected to said conduit means after said first valve means and supplying electrolyte solution thereto, (e) a second flow detecting means connected to the input of said second valve means, (f) a ratio controller means connected to said first and second flow detecting means and connected to control said second valve means, (g) means for sensing the conductivity in said conduit after the electrolyte solution has been added for controlling the electrolyte solution into the conduit, and (h) sensing head means in said conduit after the means for sensing the conductivity to determine the constituents of Ifibrous particles.

4. An apparatus for measuring predetermined constituents of fibrous particles as they pass through a paper making machine comprising: (a) a conduit means receiving a small quantity of pulp from the normal flow of pulp passing through the machine during the paper making process, (b) a first valve means in said conduit means, (c) flow detecting means connected in said conduit means before said first valve means which controls the quantity of pulp being sampled, (d) a second valve means with its output connected to said conduit means after said rst valve means and supplying electrolyte solution thereto, (e) a second fiow detecting means connected to the input of said second valve, (f) a ratio controller means connected to said first and second flow detecting means and connected to control said second valve means, (g) a supply of dilution fiuid connected to said second flow detecting means, (h) a third valve connected to said second fiow means, (i) a supply of electrolyte solution, (j) a third valve means with its input connected to the supply of electrolyte solution and its output connected to said second fiow detecting means, (k) conductivity sensing means connected in said conduit after the electrolyte solution has been added and connected to said third valve to control ing through said conduit.

S. An apparatus for measuring predetermined constituents of fibrous particles passing through a paper making machine according to claim 4 wherein said sensing heads include a pair of electrodes, and said sensing head includes an aperture through which the fibrous particles pass therethrough and said pair of electrodes produce an electrical signal indicative of fiber size as each of the fibers pass through the aperture of said sensing head.

6. An apparatus for measuring predetermined constituents of fibrous particles passing through a paper making machine according to claim 5 comprising a maximum value detector connected to said sensing head for deriving a continuous output signal having a value proportional to the maximum amplitude of a particular pulse signal and detector means connected to said maximum value detector and producing an output indicating a particular constituent of each fiber of the pulse sample.

7. An apparatus for measuring predetermined constituents of fibrous particles passing through a paper making machine comprising: (a) a conduit means receiving a quantity of pulp from the normal ow of pulp passing through the machine during the paper making process, (b) a sensing head mounted in said cond/uit for deriving pulse signal information indicative of fiber size, (c) first circuit means connected to said sensing head and responsive t the amplitude of pulse signals received from said sensin head, (d) second circuit means connected to said sensin head and responsive to the Width of the pulse signa received from said sensing heads, and (e) detecting mear connected to said rst and second circuit means and pr( ducing outputs which indicate the average length and cro: sectional area of the fiber particles being sampled.

References Cited UNITED STATES PATENTS 2,825,872 3/1958 Stubbs et al.

3,259,842 7/ 1966 Coulter et al.

3,295,059 12/ 1966 Coulter et al.

3,331,950 7/1967 Coulter et al. 324-71 I 3,345,502 10/1967 Berg et al 324-71 I OTHER REFERENCES Parks et al., Number and Size Distributions of Particl in Cellulosic Solutions, Journal of Applied Polymc Science, vol. IV Issue No. ll, pp. 193-199 (1960) Coulter Counter, Bulletin A-l, 1957 Coulter Eler tronics, Chicago, 111. (4 pages).

S. LEON BASHORE, Primary Examiner U.S. C1. X.R. 

